Explanation:
A dim double star system cataloged as Gliese 623 lies
25 light-years from Earth, in
the constellation of Hercules.
The individual stars of this
binary system
were distinguished for the first time
when the Hubble Space Telescope's
Faint Object Camera
recorded this image in June 1994.
They are separated by 200 million miles -
about twice the Earth/Sun distance.
On the right, the fainter Gliese 623b
is 60,000 times less luminous than the Sun
and approximately 10 times less massive.
The fuzzy rings around its brighter companion, Gliese 623a, are image
artifacts.
The lowest mass
stars are classified as
red dwarf stars,
but even red dwarfs are massive enough to trigger
hydrogen fusion in their cores to sustain
their feeble starlight.
Slightly less massive objects, known as
brown dwarfs, can
shine only briefly as
their central temperatures are too low to utilize hydrogen
as nuclear fuel.
The present estimates of the mass of Gliese 623b are right at
this red dwarf/brown dwarf border but future observations should
help clarify the nature of one of our Galaxy's small stars.
Dim and difficult to detect, an
abundance of objects like Gl623b has been proposed as a possible
solution to the mystery of"Dark Matter" in the Universe.